The present invention relates to metal-vapor laser discharge devices and more specifically to a discharge device having a rapid starting time and a low cost gas envelope.
Presently such laser devices are constructed with either a single or a double glass envelope as shown in my U.S. Pat. Nos. 3,683,295 and 3,798,486 respectively. Since the metal vapor lasers operate at high temperatures, such as 250.degree. C. to 300.degree. C. for a He-Cd laser, the glass envelope must have high temperature resistivity and low gas permeativity. In addition to the high temperature limiting the type of envelope used, it also causes a substantial delay period while the device is warming up. Normally the heat given off by the vapor discharge is used to heat the device to operating temperature. However, warm up time with this means often requires in excess 30 minutes for the device to reach full power. In an attempt to solve the warm up problems, external heating means have been employed. However, drafts from the external environment would often cause the laser envelope to crack.
These envelopes have had the added disadvantage of being relatively uneconomical to manufacture since the intricate configuration necessitated the use of custom formed enclosures. To facilitate mass production, it is desireable to mount reflectors directly onto the ends of the outermost envelope. However, since this envelope remains at a high temperature during the laser operation, the envelope expands and the reflectors often become misaligned or detuned.